Daniel Reetz, the founder of the DIY Book Scanner community, has recently started making videos of prototyping and shop tips. If you are tinkering with a book scanner (or any other project) in your home shop, these tips will come in handy. https://www.youtube.com/channel/UCn0gq8 ... g_8K1nfInQ

# This will ensure the left and right pages are exactly the same size.
ScaleToFirst=

# *** Output ***
Pages=all
CreatePDF = essin.pdf

Everything seems to preview ok. there are no blank crop areas and the right hand sidebar contains 34 images.
When I submit I get:
ScaleToDPI source dpi matches destination dpi. Skipping this step
CreatePDF Creating C:\bsw\pdf\essin.pdf
java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Crop The rectangular crop area must not be empty.
at java.util.concurrent.FutureTask.report(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at net.sourceforge.bookscanwizard.BSW$4.run(BSW.java:471)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IllegalArgumentException: Crop The rectangular crop area must not be empty.
at javax.media.jai.JAI.createNS(JAI.java:1087)
at javax.media.jai.JAI.create(JAI.java:973)
at javax.media.jai.JAI.create(JAI.java:1395)
at net.sourceforge.bookscanwizard.op.Crop.performOperation(Crop.java:84)
at net.sourceforge.bookscanwizard.Operation.performOperations(Operation.java:376)
at net.sourceforge.bookscanwizard.BSW.processFile(BSW.java:522)
at net.sourceforge.bookscanwizard.BSW.access$400(BSW.java:72)
at net.sourceforge.bookscanwizard.BSW$ProcessImages$1.call(BSW.java:411)
at net.sourceforge.bookscanwizard.BSW$ProcessImages$1.call(BSW.java:408)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
... 1 more
javax.imageio.IIOException: Inconsistent metadata read from stream

The problem is that the crop for the right hand side of the page is being applied to what is left after the crop of the left hand side, which is nothing since the right side has already been discarded by the left hand crop. Somehow the process needs to preserve the image of the entire page so there will be something for the right hand crop to be applied to.

I have verified this be making the second crop fit within the borders of the first crop. It then works without error. See attached before and after